Red emissive carbon dots with dual targetability for imaging polarity in living cells

Intracellular polarity has a large impact on the activity of a series of biomolecules or maintain the function of particular domains. Therefore, monitoring the changing of intracellular polarity can great improve the understanding its functions in living cell level. Herein, by employing p-phenylenediamine as precursor, we prepared a red emissive carbon dots based nanoprobe for real-time sensing polarity in living cells. With the increasing of the polarity, a large red shift of fluorescence emission wavelength was obtained and the fluorescence intensity of red emissive carbon dots decreased about 11-fold when the solvent changed from 10 % to 99 % water. The red emissive carbon dots possess high quantum yield, high photo-stability, good biocompatibility as well as robust dual targetability for mitochondria and lysosome. Finally, the red emissive carbon dots were successfully used to discriminate polarity differences between normal and cancer cell lines.